Quarterly report pursuant to Section 13 or 15(d)

Revenues - Additional Information (Detail)

v3.5.0.2
Revenues - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Deferred Revenue Arrangement [Line Items]        
Revenues from product sales     $ 0  
FHoffmann La Roche Ltd And Hoffmann La Roche Inc [Member] | Upfront Payment Arrangement [Member]        
Deferred Revenue Arrangement [Line Items]        
Collaboration agreement, license upfront payment     $ 6,500,000  
FHoffmann La Roche Ltd And Hoffmann La Roche Inc [Member] | Research Services [Member]        
Deferred Revenue Arrangement [Line Items]        
Research collaboration agreement, estimated period     20 months  
Collaboration agreement, revenue recognized $ 800,000 $ 0 $ 3,100,000 $ 0
FHoffmann La Roche Ltd And Hoffmann La Roche Inc [Member] | Research Services [Member] | Extension Term [Member]        
Deferred Revenue Arrangement [Line Items]        
Research collaboration agreement, estimated period     5 years  
FHoffmann La Roche Ltd And Hoffmann La Roche Inc [Member] | Collaborative Arrangement [Member] | Maximum [Member]        
Deferred Revenue Arrangement [Line Items]        
Contractual agreement, potential payments 420,600,000   $ 420,600,000  
FHoffmann La Roche Ltd And Hoffmann La Roche Inc [Member] | Collaborative Arrangement [Member] | Maximum [Member] | Development Milestones [Member]        
Deferred Revenue Arrangement [Line Items]        
Contractual agreement, potential payments 292,000,000   292,000,000  
FHoffmann La Roche Ltd And Hoffmann La Roche Inc [Member] | Collaborative Arrangement [Member] | Maximum [Member] | Sales Milestone Payments [Member]        
Deferred Revenue Arrangement [Line Items]        
Contractual agreement, potential payments $ 123,800,000   $ 123,800,000